Audio, video and computer magnetic recording tapes have magnetic recording layers that are given a smooth surface to provide them with higher sensitivity particularly higher output in the high-frequency range. However, such smooth surfaced magnetic recording tapes cannot be wound or rewound smoothly and variations in tape tension reduces the running ability of the tape and causes fluctuations in tape output. Further, such tapes are easily deformed or damaged.
To overcome the above defects, a magnetic recording tape has been proposed which has a back coating on the surface of the non-magnetic base opposite the magnetic layer. However, such a conventional back coating needs improvement since it is not resistant to scraping, suffers from increased friction coefficient and tape edge bends (waving and folding); for this reason, such a tape winds or rewinds in an irregular fashion.
It is generally accepted that when a magnetic recording medium provided with a back coating for improved running properties and durability during running is rolled into a tape pack or when sheets of such a medium are stacked, unevenness in the back coating is transferred to the surface of the magnetic layer and damages the surface thereof, resulting in a reduction in magnetic properties, especially the signal to noise (S/N) ratio of the magnetic recording medium. To provide better running properties, the back coating is often given a rough surface, and thus when a roll or sheets of such a magnetic medium are stored or left to stand for extended periods of time, unevenness in the back coating is transferred to the surface of the magnetic layer which results in reducing the S/N ratio.